In this blog post, we’ll take a concise look at the principles, diagnostic process, and expected benefits of “the evolution of diagnostic technology using DNA chips.”
As human medical technology has advanced dramatically, we are getting closer to overcoming intractable diseases such as cancer and expanding treatment options for conditions that were once considered incurable. However, unlike reports on treatment technologies, advancements in diagnostic technology are not widely known to the public. Here, we will examine the key developments in DNA chips, one of the diagnostic technologies that have evolved alongside these advancements.
In the past, patient diagnosis was primarily conducted through in-person visits to hospitals, a method that carried risks such as misdiagnosis based on a doctor’s personal judgment, long waiting times, and high costs. Biochip technology is gaining attention as a solution to these limitations, and some companies are already focusing on it as a core industry for future profit generation.
A biochip refers to a biological microchip that integrates biological molecules such as DNA or proteins onto a small substrate, enabling the analysis of genetic defects, protein distribution, and reaction patterns. This article focuses on “DNA chips” among various types of biochips—devices that integrate DNA to detect genetic defects and diagnose genetic diseases.
DNA is a molecule that contains an individual’s genetic information, which is determined by the sequence of four nucleotides: A, T, G, and C. DNA consists of two strands, and because complementary base pairs (A-T and G-C) form, single-stranded DNA with a matching sequence can bind to each other (hybridization). By utilizing this property, the genetic status can be determined by measuring the extent to which the DNA being tested binds to a reference sequence pre-deposited on the substrate.
However, there is a reason why extracted genomic DNA cannot be used directly for diagnosis. DNA, which consists of exons and introns, undergoes transcription, during which introns are removed and exons are joined to form RNA; the core of the Central Dogma is that this RNA conveys the information necessary for protein synthesis. Therefore, for diagnostic purposes, a sequence consisting solely of the exons—which actually contain genetic information—is required. To achieve this, the extracted DNA undergoes transcription and reverse transcription to synthesize cDNA by adding complementary bases to single-stranded RNA, thereby yielding a target molecule composed solely of exons that is suitable for diagnosis.
The specific diagnostic process is as follows. First, DNA is extracted from standard samples of a person with a genetic disease and a healthy individual, and cDNA is prepared for each through transcription and reverse transcription. The sequence of a specific gene known from research is isolated and immobilized on a substrate, and the cDNA from the affected individual and the healthy individual are labeled with fluorescent dyes of different colors and arranged at the same location. For example, the cDNA from the affected individual is labeled red and that from the healthy individual green, and both types of single-stranded DNA are placed in a single well. When the cDNA from the person seeking diagnosis is synthesized and hybridized with the single-stranded DNA on the substrate, the labeled color corresponding to the complementary base pair is expressed. If only the single strand from the diseased side binds in a well, causing red to appear, this indicates a pathological mutation in that gene region; if both strands bind, causing yellow (green + red) to appear, this indicates a normally expressed region; and if only the normal strand binds, causing green to appear, this indicates the absence of the disease gene.
Compared to traditional hospital-based diagnostics, DNA chip technology offers the advantages of enabling remote diagnosis and providing objective data. It is also significant in terms of time efficiency; while confirming the presence of a disease using traditional methods can take several days even with multiple researchers, DNA chips often allow for analysis within a few hours, making them a promising diagnostic technology for the future.
As such, DNA chips have great potential to contribute to the health of the Korean public by enhancing the accuracy and convenience of diagnosis, and they are expected to play an increasingly important role in the fields of diagnostics and personalized medicine in the future.
